CN103928771A - Grounding method of reducing local impact grounding resistance of power plant and substation - Google Patents

Grounding method of reducing local impact grounding resistance of power plant and substation Download PDF

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Publication number
CN103928771A
CN103928771A CN201310008996.6A CN201310008996A CN103928771A CN 103928771 A CN103928771 A CN 103928771A CN 201310008996 A CN201310008996 A CN 201310008996A CN 103928771 A CN103928771 A CN 103928771A
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China
Prior art keywords
grounding
power plant
resistance
earth
horizontal grounding
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Pending
Application number
CN201310008996.6A
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Chinese (zh)
Inventor
李景禄
郑家松
林冶
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State Grid Corp of China SGCC
State Grid Fujian Electric Power Co Ltd
Xiamen Power Supply Co of State Grid Fujian Electric Power Co Ltd
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State Grid Fujian Electric Power Co Ltd
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Priority to CN201310008996.6A priority Critical patent/CN103928771A/en
Publication of CN103928771A publication Critical patent/CN103928771A/en
Pending legal-status Critical Current

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Abstract

The invention discloses a grounding method of reducing local impact grounding resistance of a power plant and a substation, which comprises an inner-layer annular horizontal grounding body, an outer-layer annular horizontal grounding body, a horizontal connection body and a vertical grounding body. According to the grounding method of reducing local impact grounding resistance of a power plant and a substation, local impact grounding resistance of a power plant and a substation can be reduced, diffusion of local impact grounding current is enhanced, a grounding grid local electric potential can be prevented from rising, and safety of primary and secondary devices such as a transformer can be protected; electric potential and electric field distribution around a grounding electrode can be improved, the step voltage, device contact voltage values and the like can be reduced; and the grounding method of reducing local impact grounding resistance of a power plant and a substation has the advantages of wide application range, convenient construction, corrosion resistance, safety and reliability, and long service life.

Description

Reduce the earthing method of power plant, transformer station's local assault earth resistance
Technical field
The present invention relates generally to and reduces impulse earthed resistance field, refers in particular to a kind of method that reduces lightning conducter in power plant, transformer station, lightning rod or arrester ground downlead and enter to be located in impulse earthed resistance.
Background technology
Along with electrical network transmission capacity constantly increases, stability of power system requires to improve step by step, the system failure that human factor causes reduces step by step, and the fault ratio that thunderbolt causes is increasing step by step, the earth resistance that earthing device presents when being struck by lightning in power plant, when transformer station is called impulse earthed resistance, in the time that lightning current enters ground by lightning conducter, lightning rod or arrester ground downlead, the voltage of the electric equipments such as its periphery transformer for: (circuit diagram is shown in accompanying drawing 3)
In formula, for residual voltage of arrester, kV; for direct lightning strike electric current, its direct lightning strike amplitude is generally greater than 10KA; for the impulse earthed resistance of the earthing device such as lightning rod, lightning arrester or lightning conducter, Ω; L is the inductance of down conductor, .If by 1. known its impulse earthed resistance of formula is excessive, the voltage being attached on the electric equipments such as transformer also can be too high, voltage repeatedly exceedes the rated lightning impulse withstand voltage value of Transformer Winding, and transformer is just likely broken; In addition, earthing device impulse earthed resistance is excessive, can cause the potential anomalies of earthing device peripheral region to raise, and causes the partial potential difference of grounding system itself to exceed safety value, also can form counterattack, further expansion accident to secondary system equipment; The earthy rising of substation grounding device, easily forms dangerous step voltage and equipment touch voltage at transformer station's corresponding site, and near like this staff's personal safety exists hidden danger.Therefore, reduce the impulse earthed resistance of earthing device under lightning current effect to protecting first and second electric equipment in power plant, transformer station most important.
Weakness based on above-mentioned power plant, transformer station in lightning protection; patent of the present invention enters to be located in impulse earthed resistance to reducing lightning conducter, lightning rod or arrester ground downlead in power plant, transformer station; protection electric equipment safety and ground connection all have larger actual application value in pressure aspect, personal safety are also played to good protective effect simultaneously.
Summary of the invention
The present invention is directed to lightning conducter in power plant, transformer station, lightning rod or arrester ground downlead and enter to be located in that local assault earth resistance is too high jeopardizes the normal operation of electric equipment and cause near step voltage earthing device, the too high harm causing of equipment touch voltage, provide one can reduce power plant, transformer station's local assault earth resistance, also can reduce a kind of new earthing method of power plant, near the step voltage of substation grounding device and equipment touch voltage simultaneously.
For solving power plant, the problem that transformer station's local assault earth resistance is too high, the invention provides a kind of new earthing method, it is at lightning conducter, lightning rod or arrester ground downlead enter to be located in depths, approximately 1 meter, peripheral distance earth's surface and lay an inside and outside double-layer circular earth electrode (seeing accompanying drawing 1), then (5 meters of compartment distances between inside and outside ring-type earth electrode, can suitably dwindle if be subject to landform restriction) lay level connection joint body inner and outer ring is linked together, and on outer ring-type horizontal grounding objects compartment distance join to original earth mat, embed again the vertical grounding electrode of 1 1.2-1.5m at each tie point place, horizontal grounding objects and vertical grounding electrode are welded together effectively, and horizontal grounding objects is coated with resistance reducing agent.Ground network adopts double-layer circular earth electrode to be aided with vertical grounding electrode, has both reduced local assault earth resistance, has strengthened the diffusion of impulse grounding electric current, has protected the safe operation of first and second electric equipments such as transformer; Increase diffusing cross section, improved impact Potential distribution and the Electric Field Distribution of grounding electrode surrounding.
Technical scheme of the present invention is:
Inside and outside double-layer circular horizontal grounding objects, between ectonexine, compartment is apart from connecting with horizontal connector, and junction embeds vertical grounding electrode, and horizontal grounding objects and vertical grounding electrode are effectively welded together.(as shown in Figure 1)
In actual earth work, horizontal grounding objects is to use band steel mostly, and Grounding Grids uses angle steel mostly, for the ease of calculating, the equivalent radius equivalence that can obtain band steel and angle steel becomes circular earth electrode, and therefore above-mentioned earthing device ectonexine all can be regarded circular ring electrode as, and annulus is by diameter round conductor curve, the diameter of ring , the electric current in annulus inflow place is I; Due to the symmetry of annulus, the inevitable girth along annulus of electric current I is evenly wandering.For ease of calculating, can suppose that it is in infinitely great uniform soil resistivity in and electric current concentrate shed by the axis of round conductor, along axis dispersed current of grounding grids density will be therefore:
Can obtain annulus surrounding space any point from accompanying drawing 6 current potential be:
Order above formula can change into:
(wherein (elliptic integral of the first kind))
If the current potential that the current potential of annulus is ordered with its surperficial P represent, get Z=a, r=b, the current potential of annulus is
Wherein
Easy in order to calculate, consider and work as b>>a have
And have
The annulus grounding electrode that is h for buried depth, in fact earth electrode under earth's surface, has certain buried depth , the impact of ground surface can not be ignored.Now ground surface becomes the bisector plane of the total space, and we call half-space problem such problem.On the interface at ground surface and air, except electric current flows into point, function of current density meets:
This be equivalent to have on ground surface one with the current source of earthing device about ground surface symmetry, and be full of resistivity and be medium.Because current source is imaginary, be referred to as mirror current source, the method for the impact of this processing ground surface is referred to as image method.
In the time calculating, need to consider the effect (as shown in Figure 7) of mirror image.
Like this, taking into account the current potential of round loop electrode after mirror image will be
With the girth of annulus substitution can obtain
In like manner can try to achieve the resistance (seeing accompanying drawing 5) of peripheral annulus
The earth resistance that can obtain single vertical grounding electrode by above-mentioned potentiometric analysis method is:
Consider the Grounding Grids parallel connection that n root annular is equidistantly arranged, introduce usage factor , omit complicated calculating and derivation, and do corresponding simplification, the earth resistance after the vertical earth rod parallel connection of n root in the time processing for:
Consider a shield effectiveness of inside and outside circle ring electrode and n root Grounding Grids, quote shielding factor , omit complicated calculating and derivation, and do corresponding simplification in the time processing, simultaneously with reference to some relevant empirical equations, the earth resistance that has proposed comparatively brief form calculates formula:
Consider again to add the resistance effect of falling of resistance-reducing anti-corrosion agent, after this resistance reducing agent is placed into the soil, can spread and utilize horizontal short circuit terrain to be connected in the crack of around original state soil layer and rock stratum, play the effect that improves surrounding soil resistivity.According to test data and use experience in the past, available one is fallen resistance coefficient represent the resistance reducing effect of resistance reducing agent, resistance-reducing anti-corrosion agent is applied to power plant, transformer station part falls in resistance device and falls resistance coefficient with resistance reducing agent layer thickness (cm) relational expression is:
Use the grounding resistance after resistance reducing agent to be:
Impulse earthed resistance
Wherein , the coefficient relevant with earth electrode shape.
To sum up can obtain:
Compared with prior art, tool of the present invention has the following advantages:
By formula
known:
(1) reduce, the pressure drop that is added in the electric equipments such as transformer when thunderbolt also can reduce, lightning conducter, lightning rod or arrester ground downlead access earthing device directly into ground simultaneously, L also can correspondingly reduce, while so just having greatly reduced thunderbolt, be added in the voltage on the electric equipments such as transformer, the voltage appending on transformer just can not exceed section ripple withstand voltage of transformer, the possibility of avoiding transformer to be broken by thunderbolt.
(2) minimizing of the impulse earthed resistance value of earthing device, the potential rise of earthing device peripheral region while having avoided thunderbolt, avoids secondary system equipment to cause the possibility of counterattack, thereby protects the safety of secondary device.
(3) above-mentioned double-layer circular earth electrode is aided with the earthing device of vertical grounding electrode, when lightning current has effectively reduced spreading resistance during by earthing device, effectively increase diffusing cross section simultaneously, also make can spread more equably into place impulse current, improve the impact Potential distribution that enters place periphery, reduced and entered peripheral region, place step voltage and equipment touch voltage value, the safety of the person plays good protection.
(4) double-layer circular structure filling resistance reducing agent, not only improve near the soil parameters of the soil of earthing device, reduce the impulse earthed resistance that enters place earthing device, increase the effective cross-section of earth electrode, play well all pressure effects, can also reduce the corrosion rate of earth electrode, extend the useful life of earthing device simultaneously.
Brief description of the drawings
Fig. 1 earthing device overall structure top plan view
Fig. 2 earthing device structure cutaway view
Fig. 3 lightning current is through earthing device diffusing equivalent circuit diagram
The annulus (internal layer) of Fig. 4 in equably
The annulus (skin) of Fig. 5 in equably
Fig. 6 annulus potential calculation around
Fig. 7 earthing device and mirror image model schematic diagram.
Embodiment
As shown in Figure 1, the present invention is in power plant, lightning conducter in transformer station, lightning rod or arrester ground downlead enter to be located in (2) and lay double-layer circular horizontal grounding objects (3) (6) in certain depths, distance earth's surface around, and down conductor is entered to place (2) be connected to internal layer ring-type horizontal grounding objects (3), between internal layer ring-type horizontal grounding objects (3) and outer ring-type horizontal grounding objects (6), compartment is apart from being connected with horizontal connector (5), be connected with original earth mat in the upper compartment distance of outer ring earthing body (6) simultaneously, embed vertical grounding electrode (1) and effectively weld together with horizontal grounding objects at each tie point place, its cutaway view as shown in Figure 2, horizontal grounding objects (9) is applied to resistance reducing agent, horizontal grounding objects (9) is excavated to trapezoidal shape groove as shown in Figure 2, carry out again laying and the welding of horizontal grounding objects (9) and Grounding Grids (11), then, horizontal grounding objects pad ground, pour resistance-reducing anti-corrosion agent (8) (10) into, in the middle of horizontal grounding objects (9) is wrapped in equably, then add water and spread and sink in, with fine earth (7) backfill, and compaction in layers.
Operation principle of the present invention is: in power plant, transformer station, lightning conducter, lightning rod or arrester ground downlead enter to be located in periphery transformation, use after inside and outside double-layer circular horizontal grounding objects, when lightning current is in the time that earth electrode enters ground, not only effectively reduce impulse earthed resistance, and strengthened the diffusion of impulse grounding electric current, and increase diffusing area, making can more even diffusing into place electric current, prevent that earth mat local potential from raising, the safety of first and second equipment such as protection transformer; Utilize absorbability and the water-retaining property of resistance reducing agent, not only improve near the soil parameters of the soil of earthing device, reduce the impulse earthed resistance of earthing device, increase the effective cross-section of earth electrode, play all pressure effects preferably, can also reduce the corrosion rate of earth electrode, extend the useful life of earthing device simultaneously; On double-layer circular horizontal grounding objects, weld the vertical grounding electrode of equidistant equal length, reduce the diffusing amount of the horizontal grounding utmost point, reduce earth potential liter (GPR), improve the Potential distribution uniformity of earthing device periphery, thereby can reduce better into peripheral region, place touch voltage and step voltage value, the safety of the person plays good protection.
The above is only the preferred embodiment of the present invention, and protection scope of the present invention is also not only confined to above-described embodiment, and all technical schemes belonging under thinking of the present invention all belong to protection scope of the present invention.Should be understood that; for those skilled in the art; some improvements and modifications without departing from the principles of the present invention, for example, change shape or the increase of earth electrode or reduce quantity of vertical grounding electrode etc., and these improvements and modifications also should be considered as protection scope of the present invention.

Claims (5)

1. a new reduction power plant, the earthing method of transformer station's local assault earth resistance, it is characterized in that: in power plant, lightning conducter in transformer station, lightning rod or arrester ground downlead enter to be located in (2) and lay double-layer circular horizontal grounding objects (3) (6) in certain depths, distance earth's surface around, and down conductor is entered to place (2) be connected to internal layer ring-type horizontal grounding objects (3), between internal layer ring-type horizontal grounding objects (3) and outer ring-type horizontal grounding objects (6), compartment is apart from being connected with horizontal connector (5), be connected with original earth mat in the upper compartment distance of outer ring earthing body (6) simultaneously, embed vertical grounding electrode (1) and effectively weld together with horizontal grounding objects at each tie point place.
2. the earthing method of reduction according to claim 1 power plant, transformer station's local assault earth resistance, is characterized in that: lay double-layer circular horizontal grounding objects, (concrete distance is depending on terrain environment) keeps at a certain distance away between inside and outside layer ring.
3. the earthing method of reduction according to claim 1 power plant, transformer station's local assault earth resistance, is characterized in that: horizontal grounding objects, level connection joint body resistance reducing agent are coated.
4. the earthing method of reduction according to claim 1 power plant, transformer station's local assault earth resistance, is characterized in that: embed the vertical grounding electrode of certain length at the each tie point of inside and outside double-layer circular earth electrode place and effectively weld with horizontal grounding objects.
5. double-layer circular horizontal grounding objects according to claim 2, is characterized in that: compartment distance between double-layer circular horizontal grounding objects (concrete distance is depending on terrain environment) connects with horizontal connector.
CN201310008996.6A 2013-01-10 2013-01-10 Grounding method of reducing local impact grounding resistance of power plant and substation Pending CN103928771A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104901030A (en) * 2015-06-09 2015-09-09 河北省电力勘测设计研究院 Construction method of resistance reduction and grounding device of transformer station
CN106468748A (en) * 2016-09-22 2017-03-01 国网山东省电力公司经济技术研究院 A kind of method for equalizing voltage of transformer station main grounding grid
CN111786349A (en) * 2020-06-09 2020-10-16 深圳供电局有限公司 Step voltage suppression method for power transmission line tower

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Publication number Priority date Publication date Assignee Title
CN1599164A (en) * 2004-08-23 2005-03-23 孟庆彬 High mountain lightning-protection device
US20080164046A1 (en) * 2007-01-06 2008-07-10 Duley Wayne C Grounding and energy dispersion system
KR200443914Y1 (en) * 2008-10-07 2009-03-24 (주)우림종합엔지니어링 Grounding apparatus for electric power pole skilled falling down prevention
CN201383556Y (en) * 2009-04-03 2010-01-13 新疆电力科学研究院 Deep well grounding resistance-reducing device
CN201975524U (en) * 2011-04-29 2011-09-14 贵州电网公司输电运行检修分公司 Arrangement structure for lightning protection grounding device of power tower
CN202308338U (en) * 2011-11-15 2012-07-04 傅玉洁 Double-layer structure grounding grid with characteristics of effectively improving electric potential distribution and reducing step voltage
CN102593618A (en) * 2011-12-03 2012-07-18 李景禄 Grounding method for decreasing step voltage of transmission line tower
CN202487783U (en) * 2011-11-15 2012-10-10 李景禄 Grounding voltage-sharing device capable of reducing power transmission line tower step voltage
CN102856671A (en) * 2012-04-25 2013-01-02 辽宁省电力有限公司丹东供电公司 Environment-friendly leak-proof moisturizing grounding device and construction method

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1599164A (en) * 2004-08-23 2005-03-23 孟庆彬 High mountain lightning-protection device
US20080164046A1 (en) * 2007-01-06 2008-07-10 Duley Wayne C Grounding and energy dispersion system
KR200443914Y1 (en) * 2008-10-07 2009-03-24 (주)우림종합엔지니어링 Grounding apparatus for electric power pole skilled falling down prevention
CN201383556Y (en) * 2009-04-03 2010-01-13 新疆电力科学研究院 Deep well grounding resistance-reducing device
CN201975524U (en) * 2011-04-29 2011-09-14 贵州电网公司输电运行检修分公司 Arrangement structure for lightning protection grounding device of power tower
CN202308338U (en) * 2011-11-15 2012-07-04 傅玉洁 Double-layer structure grounding grid with characteristics of effectively improving electric potential distribution and reducing step voltage
CN202487783U (en) * 2011-11-15 2012-10-10 李景禄 Grounding voltage-sharing device capable of reducing power transmission line tower step voltage
CN102593618A (en) * 2011-12-03 2012-07-18 李景禄 Grounding method for decreasing step voltage of transmission line tower
CN102856671A (en) * 2012-04-25 2013-01-02 辽宁省电力有限公司丹东供电公司 Environment-friendly leak-proof moisturizing grounding device and construction method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104901030A (en) * 2015-06-09 2015-09-09 河北省电力勘测设计研究院 Construction method of resistance reduction and grounding device of transformer station
CN106468748A (en) * 2016-09-22 2017-03-01 国网山东省电力公司经济技术研究院 A kind of method for equalizing voltage of transformer station main grounding grid
CN111786349A (en) * 2020-06-09 2020-10-16 深圳供电局有限公司 Step voltage suppression method for power transmission line tower
CN111786349B (en) * 2020-06-09 2021-12-07 深圳供电局有限公司 Step voltage suppression method for power transmission line tower

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Application publication date: 20140716